2,3,5,6-tetrafluoro-4-methoxymethyl benzyl alcohol is a key intermediate for synthesizing tetrafluoroanisolethrin, metofluthrin and meperfluthrin. Tetrafluoroanisolethrin and metofluthrin are developed by Sumitomo Chemical Industry Co., Ltd. Meperfluthrin is developed by Jiangsu Yangnong Chemical Co., Ltd. Three of them are all low-toxicity high-efficiency pyrethroids pesticides, which have excellent knockdown and killing activity on sanitary insect pests such as mosquito and flies, and have been widely applied to controlling sanitary insect pests at present.
At present, several methods for synthesizing 2,3,5,6-tetrafluoro-4-methoxymethyl benzyl alcohol reported in documents are as follows:
(1) The document (J. Fluo. Chem. 130 (2009), 938-941) reported synthesis of 2,3,5,6-tetrafluoro-4-methoxymethylbenzyl alcohol by using 2,3,5,6-tetrafluorobenzyl alcohol as a raw material via three reaction steps of methyl etherification, carboxylation and carboxy reduction.

This method has a long reaction step, needs to use dangerous reagents such as strong bases and strong reducing agents in the process of synthesis, requires harsh conditions such as low temperature, and has high control requirements on reaction processes and high synthesis cost, and thus is only suitable for research rather than industrial production.
Invention patent JP 2000344703 reported synthesis of 2,3,5,6-tetrafluoro-4-methoxymethylbenzyl alcohol by using tetrafluoroterephthalyl alcohol as a raw material via halogenation and methoxylation.

This method is short in synthesis step and obtains the product by only two steps. Furthermore, the used reagents are all industrialized conventional raw materials which are cheap and available, so this method is low in synthesis cost and suitable for industrial production. The disadvantages are that the chemical property of hydroxyl in tetrafluoroterephthalyl alcohol is similar to that of hydroxyl in the halogenation product 2,3,5,6-tetrafluoro-4-halomethylbenzyl alcohol, their selectivity is poor when halogenation reaction is carried out, dihalogenation byproducts are easily generated, and the byproduct 1,4-bis(methyoxymethyl)-2,3,5,6-tetrafluorobenzene is further generated when the subsequent methoxylation reaction is carried out, thereby, leading to reduced reaction yield and increased synthesis cost.
(3) 2,3,5,6-tetrafluoro-4-methoxymethylbenzyl alcohol is obtained by using tetrafluoro tetraphthalyl alcohol, as a raw material via selective methylation reaction in the presence of the methylation reagent.

For example, invention patent CN1297875A, which is applied from Sumitomo Chemical Industry Co., Ltd. of Japan, uses dimethyl sulfate as the methylation reagent: invention patent CN101913997A, which is applied from Guizhou bositer chemical industry, uses methyl chloride as the methylation reagent. This method is short in synthesis steps, obtains the product by using only one step reaction, cheap and available in used reagent, and is a main method for industrially synthesizing 2,3,5,6-tetrafluoro-4-methoxymethylbenzyl alcohol at present. The main disadvantages are that in the process of reaction, the chemical property of hydroxyl in raw material tetrafluoroterephthalyl alcohol is similar to that of hydroxyl in the product 2,3,5,6-tetrafluoro-4-halomethylbenzyl alcohol, leading to poor selectivity in the process of reaction and easily generation, of byproduct 1,4-bis(methyoxymethyl)-2,3,5,6-tetrafluorobenzene. Typically, the content of this byproduct is about 10%, which results in reduced reaction cost and increased synthesis cost.
At present, in the industrial manufacturing process of 2,3,5,6-tetrafluoro-4-methoxymethylbenzyl alcohol, the byproduct 1,4-bis(methoxymethyl)-2,3,5,6-tetrafluorobenzene is generated. According to the different process routes and process conditions, the byproduct usually accounts for 5-15%. At present, its application value has not been found, so it can only be burned as hazardous waste, which not only pays a large amount of treatment cost but also possibly generates secondary pollution in the process of incineration disposal. Thus, how to perform resource utilization of 1,4-bis (methoxymethyl)-2,3,5,6-tetrafluorobenzene has become an urgent problem.